mime-info/user.keys can't be modified, please help.

[Paul Huang <Paul Huang SUN COM>]

Hi All

I am now using gnome_vfs_mime API to access/modify the mime info on 
Redhat 8.0.

My problem is

1. Can not modify $home/.gnome/mime-info/user.keys
I tried to modify the user.keys by gnome_vfs_mime_set_description but
the file keeps unchanged. If I use gnome_vfs_mime_set_icon, the file
user.mime would be changed accordly.

2. Can't delte user.keys
I tried to remove the file user.mime, the remove action carried out
successfully.
If I try to delete user.keys, the result is that the system will 
automatically generate a new user.keys. I can never delete the file
user.keys.
The new generated user.keys would be sth like

#this file was autogenerated by gnome-vfs-mime-info.
#Do NOT EDIT BY HAND
text/
   default_application_id=openoffice
   default_action_type=component

I doubt if there is some backend process that keeps me from
modifying the file user.keys.

Can anybody give me any idea about

1. What should I do in this case to modify the file user.keys

2. Is this a bug of openoffice or gnome_mime_vfs?

Regards

-Paul